The pH of a water is measured to be 7.5. The concentration of bicarbonate was measured to be 1.3x10' M. What are the concentrations of carbonate, carbonic acid and TOTCO3 if you assume the system is closed to the atmosphere? What is the dominant species and why? Consider now a system open to the atmosphere. The pH of a water is 7.5. What are the concentrations of carbonate, bicarbonate, carbonic acid and TOTCO3? The temperature is 25C. The partial pressure for carbon dioxide is 10-3.53